1. Field of the Invention
The present invention is directed to an expansion joint system for bridges, roadways, parking structures and the like wherein adjacent roadway slabs are subject to movement yet a flexible seal is required in the expansion gap between adjacent roadway slabs. In particular, the present invention is directed to an expansion joint system which decreases the cost of like joints while providing a high strength, impact resistant, semi-flexible joint nose and allow various liquid or preformed seals to be used in the gap to absorb the movement.
2. Prior Art
Roadways, bridges and parking structures are customarily built of sections or slabs arranged with an expansion gap between adjacent slabs. It is known that the slabs will expand and contract in response to temperature changes. In many applications, such as bridges and parking structures, loading due to vehicular traffic also causes vertical movement of the slabs.
Notwithstanding the movement of the slabs, a flexible joint which will retain a watertight seal is highly desirable. A watertight seal will prevent water from getting beneath the slabs and rusting bridges or parking structure components. In freezing conditions, the water will cause damage because of heaving. Additionally, road salts are highly corrosive to bridge elements. A seal in the expansion joint will also prevent debris from lodging in the joint and causing problems.
Many materials in various arrangements have heretofore been used to seal roadway, bridge and parking structure expansion joints. Some of the materials lose their adhesion and quickly require replacement. As an example, in applications with an asphalt overlay, the seal might hold but the asphalt may crumble away.
In new roadway, bridge and parking structure construction, time may not be a critical factor in installation of the joint seal. In remedial applications, however, time is a critical factor so that downtime must be minimized, particularly where vehicular traffic has to be returned as soon as possible.
Various expansion joints have heretofore been proposed. As an example, Gibbon (U.S. Pat. No. 4,699,540) discloses an expansion joint system where a preformed longitudinal resilient tube of heat cured silicone is installed in the recess. An initially flowable adhesive silicone is then injected into the recess on both sides of the tube.
Galbreath (U.S. Pat. No. 4,447,172) discloses a flexible elastomeric membrane wherein adhesive may be utilized to assist in holding the membrane to the side rails.
Cihal (U.S. Pat. No. 4,963,056) provides layers of plastic concrete compound which are cast in the recess. An adhesive coating of an epoxy resin is coated on top of the second layer to assist in retaining a pad which spans the expansion gap.
Belangie (U.S. Pat. Nos. 4,824,283 and 4,927,291) provides a preformed strip of silicone which floats or is embedded in a silicone adhesive.
Peterson et al. (U.S. Pat. No. 4,279,533) disclose an expansion joint system wherein a metal plate secured to one concrete section bridges an expansion slot. The remainder of the recess is filled with a premolded elastomeric slab surrounded by edge portions which are molded on the job site.
Watson (U.S. Pat. No. 4,080,086) discloses a joint sealing apparatus having a pair of elongated elastomeric pads embedded with crushed rock which are secured to the concrete slabs by studs and nuts. A flexible, resilient elongated member extends between the pads.
Semi-flexible polymer concretes have been used to form or repair joints in bridges and parking decks for many years. A non-cementious binder which has various degrees of flexibility is combined with aggregates.
Cathey et al. (U.S. Pat. No. 5,190,395) discloses an expansion joint apparatus wherein a recess is filled with a polymer-based concrete mortar compound. A silicone sealant is installed between the nosings to form a flexible seal. In some cases, an unusually large volume of polymer-based mortar mixture is needed. Polymer-based mortar mixture is more expensive than ordinary concrete. Thus, when an application requires large volumes of polymer-based concrete, the cost of the application is very expensive.
It is a principal object and purpose of the present invention to provide an expansion joint system for both new construction and remedial applications which may be installed quickly yet is extremely durable.
It is a further object and purpose of the present invention to reduce the cost of the expansion joint system by replacing some of the polymer-based mortar mixture required to form nosings with less expensive high-strength filler blocks.